with the washing liquid. After three hours' continuous boiling the
infusion thus infected will often develope luxuriant bacterial life.
Precisely the same occurs if a turnip infusion be prepared in an
atmosphere well charged with desiccated hay-germs. The infusion in
this case infects itself without special inoculation, and its
subsequent resistance to sterilisation is often very great. On the
1st of March last I purposely infected the air of our laboratory with
the germinal dust of a sapless kind of hay mown in 1875. Ten groups
of flasks were charged with turnip infusion prepared in the infected
laboratory, and were afterwards subjected to the boiling temperature
for periods varying from 15 minutes to 240 minutes. Out of the ten
groups only one was sterilised--that, namely, which had been boiled
for four hours. Every flask of the nine groups which had been boiled
for 15, 30, 45, 60, 75, 90, 105, 120, and 180 minutes respectively,
bred organisms afterwards. The same is true of other vegetable
infusions. On the 28th of February last, for example, I boiled six
flasks, containing cucumber infusion prepared in an infected
atmosphere, for periods of 15, 30, 45, 60, 120, and 180 minutes. Every
flask of the group subsequently developed organisms. On the same day,
in the case of three flasks, the boiling was prolonged to 240, 300,
and 360 minutes; and these three flasks were completely sterilised.
Animal infusions, which under ordinary circumstances are rendered
infallibly barren by five minutes' boiling, behave like the vegetable
infusions in an atmosphere infected with hay-germs. On the 30th of
March, for example, five flasks were charged with a clear infusion of
beef and boiled for 60 minutes, 120 minutes, 180 minutes, 240 minutes,
and 300 minutes respectively. Every one of them became subsequently
crowded with organisms, and the same happened to a perfectly pellucid
mutton infusion prepared at the same time. The cases are to be
numbered by hundreds in which similar powers of resistance were
manifested by infusions of the most diverse kinds.

In the presence of such facts I would ask my colleague whether it is
necessary to dwell for a single instant on the one-sidedness of the
evidence which led the conclusion that all living matter has its life
destroyed by 'the briefest exposure to the influence of boiling
water.' An infusion proved to be barren by six months' exposure to
moteless air maintained at a temperatur